- Age-related macular degeneration (AMD) can lead to varying stages of vision loss.
- A new study has indicated how two natural deposits, drusen and SSDs, influence AMD’s development.
- The deposits affect a type of fluorescent light naturally produced by the retina.
- The findings will allow doctors to diagnose and treat those with AMD better.
Around 20 million Americans over the age of 40 live with age-related macular degeneration (AMD), according to
Of that number, about 1% experience vision-threatening AMD.
AMD is an eye condition that occurs when part of the retina
However, a new
“AMD is the leading cause of severe visual loss in the population over the age of 65,” stated Dr. Janet S. Sunness, medical director of Hoover Low Vision Clinic at Greater Baltimore Medical Center and a specialist in low vision, macular and retinal disease.
“In its early stages, it causes only a mild reduction of vision and a need for good lighting,” she told Healthline. “In its advanced stages, it causes blind areas in the central vision, leading to difficulties with reading, recognizing faces, and performing other fine tasks.”
There are two varieties of AMD: wet and dry.
“Dry AMD consists of drusen and atrophy and tends to be slowly progressive,” said Dr. Philip Storey, a board-certified ophthalmologist and fellowship-trained retina specialist, who was not involved in the study. Meanwhile, “wet AMD is characterized by bleeding and fluid on the back of the eye with rapid vision loss.”
Sunness explained that all AMD patients have the dry form of the condition to begin with. Wet AMD is then considered an advanced stage, along with advanced dry macular degeneration.
Two types of deposits, called ‘drusen’ and ‘subretinal drusenoid deposit’ (SSD), have previously been noted as a sign of AMD.
The researchers looked at various parts of 23 different eyes in 18 patients with advanced AMD, and saw that these deposits impacted a fluorescent light in the eye called autofluorescence (AF), that is naturally produced by the retina.
“When the retina is ‘sick’, the fluorescence of the retina may be abnormal,” said Storey.
“Brighter signals are emitted when lipofuscin [a byproduct of photoreceptor breakdown] accumulates,” he said. “Darker signals [are emitted] when there is complete photoreceptor death, called atrophy.”
Autoflorescence “is too dim to see with the naked eye, so we created sensitive diagnostic tools to see it,” explained Dr. R. Theodore Smith, PhD, professor of ophthalmology at the Icahn School of Medicine at Mount Sinai, and co-author of the study.
Smith explained that in people with AMD there are abnormal patches of lighter or darker AF.
In the new research, the AF light measured was twice as bright in eyes with SSDs as the AF seen in those with drusen deposits.
Smith asserted that the research findings are significant as they “clearly show that SDDs and drusen are different diseases. This means they must be diagnosed and treated separately.”
What to know about drusen and SSD
These deposits may be small but can greatly impact vision.
So what exactly are they?
“Drusen are small, yellow deposits that can form between the retina and the choroid, the layer of blood vessels that supplies the retina,” Dr. Michael Cooney, a vitreoretinal surgeon with Vitreous Retina Macular Consultants of New York, explained to Healthline.
“They are made up of a variety of protein and lipid components, including lipids, collagen, and proteoglycans,” he added.
SSDs are similar, stated Cooney, but they form underneath the retina and “are composed mainly of lipids and protein.”
Cooney revealed that drusen and SSD are thought to occur as a result of three factors:
- Chronic inflammation
- Accumulation of waste products in the retina
- Damage to the retinal pigment epithelium (RPE) cells that support the retina.
When it comes to their impact on vision, Smith revealed that SSDs are more detrimental. “Compared to drusen, SDDs double the rate of progression to advanced AMD, and have a strong correlation with major life-threatening vascular diseases.”
SSDs can be an early warning sign for undetected cardiovascular or cerebrovascular disease, explained Dr. Sam Dahr, an ophthalmologist and director of the retina division with McGovern Medical School at UTHealth Houston.
As such, the patient “may be recommended to have a closer follow-up with an internist or cardiologist,” he noted.
Various factors are thought to increase an individual’s risk of AMD. According to Sunness and Cooney, these include:
- Cardiovascular disease
- High exposure to sunlight throughout your life
- Having blue eyes
- Being Caucasian
- Experiencing head or eye trauma
- Exposure to certain environmental toxins like pesticides, air pollution, and heavy metals
- Deficiencies in nutrients such as vitamin D, vitamin B12, and folic acid
- Experiencing chronic inflammation
- Certain systemic diseases, such as lupus, sarcoidosis, and autoimmune diseases
Genetics can also play a role. “Some patients may have genes that make them more susceptible to accumulating SSD and drusen deposits,” revealed Dahr.
“It’s important to note that the causes of AMD are multi-factorial and can vary from person to person,” shared Cooney. “The above-mentioned factors alone or in combination may contribute to the development of AMD.”
Although there is currently no cure for dry or wet AMD, treatments can help slow its progression.
“These can prevent a person from going blind, so represents a huge step forward for patients,” asserted Storey.
According to Cooney, treatments for AMD vary depending on the disease type and severity. Unfortunately, they are currently unable to restore vision that has already been lost.
In cases of dry AMD where large drusen deposits are present, a specific vitamin formulation may benefit some patients. Known as the AREDS 2 (Age-Related Eye Disease Study) formulation, “it consists of vitamin C, vitamin E, zinc, lutein, zeaxanthin, and a small amount of copper (to offset the zinc),” said Sunness.
Studies have shown the formulation “reduces the risk of getting wet macular degeneration by about
For advanced dry AMD — also known as geographic atrophy (GA) — there is hope for new treatment options.
“A number of studies have investigated new medications to slow the progression of GA,” revealed Storey. “We expect to have the first drug approved by the FDA this year.”
One treatment approach for this more advanced form of AMD involves FDA-approved injections.
“Since the mid-2000s, retina specialists have had a family of medicines known as the ‘anti-VEGF medications’ that can be injected into the eye to treat wet AMD,” shared Dahr.
Wet AMD may also be treated with laser therapy and photodynamic therapy, revealed Cooney. Along with the injections, “these treatments are aimed at stopping the growth of abnormal blood vessels and preserving vision.”
In both dry and wet AMD, “low vision rehabilitation can significantly improve patients’ ability to use their vision more effectively,” emphasized Sunness. These include improved lighting, stronger reading glasses, and various types of magnification.
“There is always hope for patients, and there is never ‘nothing more that we can do’,” she stated.
New research has revealed the role that two eye diseases can have on the development of AMD.
The findings are notable, said Dahr, as they “may allow researchers and clinicians in the future to distinguish eyes that have more of a drusen profile versus eyes with more of an SDD profile, and hence make more targeted recommendations.”
Measures such as not smoking, eating a healthy diet, regular exercise, and wearing protective eyewear outdoors can help stave off its development.
For those with AMD, various treatments can slow the condition’s progression. Furthermore, Storey emphasized, “having regular eye exams with a retina specialist is critically important, as this disease can result in blindness.”